1. Technical Field
The present invention relates to a liquid ejecting head, and particularly, to a liquid ejecting head which is a useful for realizing high density of a piezoelectric element.
2. Related Art
A piezoelectric element, which is displaced by applying a voltage, is mounted on, for example, a liquid ejecting head ejecting liquid droplets, or the like. As such a liquid ejecting head, for example, a recording head of an ink jet type (hereinafter, also referred to as recording head) is known, in which a part of a pressure generating chamber communicating with a nozzle opening is formed of a vibration film. In addition, the recording head discharges the ink droplets from nozzle openings by pressurizing ink which fills an inside of the pressure generating chamber in which the vibration film is deformed due to the piezoelectric element.
In this type of the recording head, in order to accomplish displacement of the vibration film when realizing a high-density of the piezoelectric element disposed on an insulating film, for example, an insulating film formed as a zirconia film needs to be thin.
JP-A-2005-260003 discloses a technology for improving characteristics of the piezoelectric layer by controlling the surface roughness of the zirconia film when regulating a film formation condition of the zirconia film, which is the insulating film.
FIG. 8 is a graph illustrating a correlation of the surface roughness Ra of the insulating film and (100) alignment ratio of a piezoelectric layer (PZT) crystal. As illustrated in the drawing, the crystal becomes good when the alignment ratio of the piezoelectric layer increases as a numerical value of the surface roughness Ra also increases. It suggests that the insulating film can be thin while controlling the crystal properties of the piezoelectric layer when the surface roughness Ra increases. That is, when the insulating film can be realized to be thin, the displacement thereof according to driving of the piezoelectric element can be great.
However, as disclosed in JP-A-2005-260003, the surface roughness Ra is less likely to be controlled using only a film formation condition of the insulating film (zirconia film), and the crystal properties of the piezoelectric layer is less likely to be improved. That is, in a technology of the related art disclosed in JP-A-2005-260003, or the like, a film thickness of the insulating film needs to be thin in order to realize a high density of the piezoelectric element; however, the surface roughness Ra is not increased when the film thickness thereof becomes thin, and the alignment ratio of the piezoelectric layer becomes small. Therefore, the film thickness of the insulating film is required to be large.